Is it possible to have both hypersomnia and insomnia? sometimes i sleep way too much for days. then i can't sleep for 3-4 days. feel anxious a lot.

It's possible: Possibly not uncommon. Your sleep has become out of control and there may also be other parts of your life that are too. A good therapist working with appropriate doctors (sleep specialists, pcp, neurologist, etc.) would be able to diagnose and treat you. It might be the only way your body can find a way to get what it needs until you get tx. Best!

Get evaluated: With such fluctuations in your sleep pattern, energy state and associated anxiety, your symptoms warrant a thorough evaluation by a medical doctor specialized in diseases that involve dysregulation of circadian rhythm (insomnia/hypersomnia) and arousal state (anxiety). This would be a psychiatrist:) you can locate and research psychiatrist who might work and live near you healthtap!